Conventionally, as a connection between an electric wire and a terminal in an automotive wire harness, a crimp joint is generally used in which a so-called open-barrel terminal is crimped with an electric wire. However, in this type of wire harness, when moisture or the like attaches to a connecting portion between the electric wire and the terminal, a surface of a metal used in the electric wire is subject to oxidization, and resistance in a joining portion increases. Further, when metals used in the electric wire and the terminal are different from each other, galvanic corrosion occurs. The progress of the corrosion of the metal materials in the connecting portion causes cracking or a contact failure of the connecting portion, and inevitably has an impact on the product life. Particularly, in recent years, a wire harness that uses an electric wire formed of an aluminum alloy and a terminal formed of a copper alloy is being commercialized, so the problem relating to the corrosion of the joining portion is becoming more notable.
Here, when moisture attaches to a contact portion between dissimilar metals, such as aluminum and copper, for example, so-called electrolytic corrosion may occur, due to the difference in corrosion potential. In particular, since the potential difference between aluminum and copper is large, the corrosion occurs on the aluminum side, which is electrically less noble. Accordingly, a connection state between the conducting wire and the crimping terminal becomes unstable, and there is a risk that an increase in contact resistance, or an increase in electrical resistance due to a decrease in a wire diameter may be caused, and further, a malfunction or a breakdown of an electrical component may occur as a result of a break in the wire.
Examples of this type of wire harness in which dissimilar metals come into contact with each other include a wire harness which is filled with a resin material so as to cover the connecting portion between the electric wire and the crimping terminal (Patent Document 1). The wire harness filled with the resin material inhibits moisture from attaching to the contact portion between the electric wire and the crimping terminal.
Further, a method has been proposed in which a terminal including a one end-closed cylindrical crimp portion is used, and an end portion of an electric wire is inserted into the cylindrical crimp portion, and then the cylindrical crimp portion is crimped by crimping so as to protect an end portion of a core wire from attachment of rain water, sea water, and the like (Patent Document 2).